This is the cast house of Carrie Furnace blast furnace number 6. In the floor are the channels or "runners" through which molten iron flowed. Sluice gates (is that the right terminology?) were used to control the flow. The iron poured directly into "torpedo" rail cars parked below this floor, for transport across the Monongahela River to Homestead Works where the iron was refined into steel and rolled into beams and sheet steel. Slag was skimmed off the top of the molten iron here in the cast house and diverted via slag runners into "slag pot" rail cars, also parked below this floor, for disposal.